1. Field of the Invention
The present invention relates to a grain size selection and/or matter drying apparatus for the treatment of suspended mineral particles whereof at least 90% in weight have a size less than 60 mm.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
In mineral matter crushing and/or drying workshops, “in-line” suspended drying apparatuses are commonly used, applied to matter whereof the average grain size is smaller than 10 mm. These apparatuses, wherein thermal exchange is mass-based, via drying, and is very quick, are often qualified as “flash” apparatuses. Such systems in the form of an arrangement of a vertical hot gas pipe have been described in publications and in particular B. Reinhardt, Ph. Duhamel, R. Evrard, A. Cordonnier—Le sechage flash (flash drying)—Seminaire de la Societe de l'Industrie Minerale (Seminar of the Society of Mineral Industry)—Dijon, 9 Oct. 1999.
For suspending the major portion of matter to be treated, and enabling contact with the hot gases for drying said matter, an ascending hot gas flow is created whereof the speed is of the order of 30 to 40 m/s, thus causing significant load loss.
Although as a matter of principle, in such systems, the coarsest fractions of matter are not carried away, these apparatuses are not considered as grain size selectors. Indeed, when these apparatuses are filled with a coarse fraction composed of particles of various diameters, generally, the major portion of the fraction falls, without separation or suspension of the finest particles contained therein.
Conversely, it also happens that coarse fractions of smaller dimensions are carried away due to the high intensity of the ascending flow. The selection power of these machines, which expresses the capacity to separate matter in relation to the size of their grains, is hence poor.
Moreover, the presence of a coarse fraction in too large quantity disturbs the operation of these apparatuses as well the operation of the plant inside which they are installed. For instance, in the case of a crushing plant for the production of cement, the apparatus will disturb the operation of the aeraulic separator situated downstream thereof. Indeed, when the drying apparatuses are loaded with a large coarse fraction, the apparatus becomes unstable, wherein the ascending flow necessary to the suspension of matter is pumping jerkily.
The aim of the present invention is to provide a grain size selection and/or pulverulent matter drying apparatus for the treatment of suspended mineral particles whereof at least 90% in weight have a size less than 60 mm, which operates in-line and stably for application to materials whereof the grain size spectrum is wide.
Another aim of the present invention is to provide a grain size selection and/or drying apparatus enabling proper separation of the particles, which can then be suspended.
Another aim of the present invention is to provide a grain size selection and/or pulverulent matter drying apparatus, constituted mainly of a vertical gas pipe, with small space requirements, in particular with a height substantially smaller than the height of the gas pipe of the “flash” type drying apparatuses known to the man of the art.
Another aim of the present invention is to provide a grain size selection and/or pulverulent matter drying apparatus, operating using an ascending gas flow whereof the speed is vastly lower than the speed of the ascending gas flow of the “flash” type drying apparatuses known to the man of the art, thus reducing the load loss.
Other aims and advantages of the invention will appear during the following description, given solely for informative purposes, and without being limited thereto.